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SMT-Sept2017

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46 SMT Magazine • September 2017
four segments. Each segment displays one
component corner. Alignment is supported in
large magnification. Matching of pins and pads
becomes much easier for the operator's eyes.
Summary and Future Outlook
Even if production quality throughout the
electronic industry is constantly rising, rework
will remain a challenging topic for the next
decades. Electronic assemblies are reaching
higher integration and a generally increasing
complexity. The rework system supplier's task
will be to follow these market movements
and offer solutions that provide the ability to
rework boards successfully. At the same time the
degree of automation will rise in the segment of
rework equipment, and operator assistance will
become more important. Besides technological
challenges as many features as possible of the
high end rework systems need to find their way
down to the entry level rework units as a spin
off. Commercial and environmental benefits
due to less scrap and electronic waste will thus
be achieved.
SMT
References
1, 2. Wikipedia: "Void" in soldering defect
and surface mount technology.
Editor's Note: This article was originally
presented at the technical proceedings of IPC APEX
EXPO 2017.
Joerg Nolte is the product
manager for tools, rework and
inspection systems at Ersa GmbH.
BTC AND SMT REWORK CHALLENGES
Research at the National Institute of Standards
and Technology (NIST) may have found that sub-
tlety solves some of the issues with a novel memo-
ry switch.
This
technology,
resistive random access mem-
ory (RRAM), could form the basis of a better kind
of nonvolatile
computer memory, where data is re-
tained even when the power is off. RRAM could
surpass flash in many key respects, it has yet to be
broadly commercialized because of technical hur-
dles that need addressing.
One hurdle is its variability. A practical memo-
ry switch needs two distinct states, representing
either a one or a zero, and component design-
ers need a predictable way to make the switch
flip. Conventional memory switches flip reliably
when they receive a pulse of electricity, but we're
not there yet with RRAM switches, which are still
flighty.
In two recent papers, the research team has
found a potential solution. The key lies in control-
ling the energy delivered to the switch by using
multiple, short pulses instead of one long pulse.
"Shorter pulses reduce the variability," NIST
guest researcher
David Nminibapiel said. "The is-
sue still exists, but if you tap the switch a few times
with a lighter 'hammer,'
you can move it grad-
ually, while simultaneously giving you a way to
check it each time to see if it flipped success-
fully."
Because the lighter touch
does not push
the switch significantly from its two tar-
get
states, the overlapping issue can be
significantly reduced. Nminibapiel added that
the use of shorter pulses also proved instru-
mental to uncovering the next serious chal-
lenge for RRAM switches—their instability.
NIST Scientists Push Us Closer to Flash Memory Successor